Gun sight



Dec. 19, 1950 D. v. GALLERY, JR

GUN SIGHT 5 Sheets-Sheet 1 Filed March 31, 1941 I I l lNVENTOR Z Gall?mag;

an/ze D. v. GALLERY, JR

Dec. 19,1950

GUN SIGHT 5 Sheets-Sheet 2 Filed March 31, 1941 lley'fn 96 ATTORNEY Dec.19, 1950 D. v. GALLERY, JR

GUN SIGHT 5 Sheets-Sheet 3 Filed March 31, 1941 lllllllllllllllmnnmmnuununnlm .Iilllilulll INVENTOR 17am V Galley J".

ATTORNEY Dec. 19, 1950 D. v. GALLERY, JR 2,534,258

GUN SIGHT Filed March 31, 1941 s Sheets-Sheet 4 ELEVAT/O/V INVENTOR YDam eZ VGalle ryJn ATTORNEY Dec. 19, 1950 D. v. GALLERY, JR 2,534,258

GUN SIGHT Filed March 31, 1941 5 Sheets-Sheet 5 I TfZO.

INVENTCm BY flanz'el VGalleyJr:

Patented Dec. 19, 1950 UNITED PATENT OFFICE GUN SIGHT Daniel"; GalleryJr., United StatesNavy Application March 31, 1941, Serial No. 386,090

(Grantedunderthe act' of March 3, 1883, as amended'April 30, 1928; 3700. G 757) 1 Claim;

This invention. relates to automatically compensating gun sights formachine guns.

In firinga flexibly mounted, or turretmounted machine gun from a movingaircraft, a certain correction must be applied to theaim. of the gun tocompensate for the velocityimparted to the projectile as a. result ofthe movement: of the aircraft. This correction is known as gunnerdeflection. The-magnitude of, the angle at. which thegun barrelis-oitset from the line of=sight to correct for the gunners deflectionis dependent upon the'direction in which. the gun is pointed relative tothe line of flight and uponthe air speed of the: firing aircraft.

, The fundamental principle: by whichthe correction iswobtained, whichis. old inthe art, is to eifectan offset ofone oi two sighting;members.. Ininy inv'entidnl have perfected an automatic means. foroffsetting. the forward sight, theoifsetbeing, alwaysin the direotionofmotion "oi?v the/aircraft. lTheamount of thefoffset may be determined.by considering a simple parallelogram. formed by the. sighting. members:in which thedistance between the axisoff the forward and rear sightingmember is. a function? of' the muzzle 'velocity'of. thebullet and. itsdirection is parallel to the axis of the bore of. the gun.' It,therefore, represents the component of motion (if the bullet due to theexplosion of the' charge in the chamber of, the gun; Th'e-lengthof theoffset of the forward sight from its axis is proportional'to thejsamefunction of velocity and represents the air speed of the craft andi'itsdirection. It' is at'all times parallel to the motion of' the aircraft,and is therefore the vector componentof the motion. of" the bullet dueto the'-motion of'the craft. The line of sight as determined by thecenter of thetwo' sighting member's isthe resultant of thetwo"components andrepresentsthe direction and velocity ofthe bullet; duetoboth forces.

This resultant is the desired sight line'to be 'laidpoint blank at thetarget; assumingth'e target to be'stationary and further 'assu'ming thatth'edefi'ection of thebullet from its straight line path due to theforce of" gravity acting on the bullet is so man" that it maybedisregarded; In ebtuar practice =--the sight line is corrected forthe'speed'and direction' of' the target by means well knownto the art;however, correctionsfifor" the force of" gravity are seldom necessary,since the ranges' at' which these sights are effective "are "relativelyshort and the 'tra-jectoriesare substantially flat.

' 1 am: hereprim'arily concerned-with the correction for' gunner'sdeflection? and my invention? consists particul'arly in improvements ofthe prior art gun rsights; especially i the gun sights I" offthetypeillustratedand' described in' 'thelf; ,8;

flexibly mounted aerial 7 patent to Inglis, 1,650,628, to which a moreparticular reference will be made laterin this specification. I havealso devised other means for introducing the correction for gunnersdeflection, which is madethesubject of my copending applicationNo..-389,844, filed April 23; 1941-.

It is an object of my invention to provide a gun sight. having twosighting members, one of which is mounted on a pivoted arm so that thesight may be offset both laterally and longitudinally as the gun ismoved in elevation or in train.

It is a further important object of this invention to provide anautomatic adjustment for-'the movable sight. member which will-maintainthe axis of the arm carrying the movable sighting member parallel to thefore and aft axis of-the aircraft, irrespective of the angle ofelevation or-train of the gun relative to the axis;

It is. also a further objectof this invention to provide a means foreasily and quickly adjusting the position of the sighting memberrelative to its support so that the length of-theofiset may be adjusted.to compensate for changing airspeeds of the aircraft.

It is another object of this invention to provide a gun sightwhichautomatically compensates for gunners deflection inaturretmountedaerial machine gun.

It isan important feature-ofmy invention that the oifset of the sightingmember always-be in a. direction of motion of the aircraft through theair, i. e., always parallel to its keelor longitudinal. axis, regardlessof the position of the gun. The automatically adjusted gun sights of theprior art have failed to accomplish this specific purpose; For example,the corrections-in- -troduced. by the device illustrated in the patentto, Inglis, 1,650,628, are only approximately-correct over a limited.rangeof elevations andtrain, while the corrections introduced by theapparatus which constitutesmy' invention are correct for any angle ofelevation or train. Certain constructional features of my inventionwhich are designed to produce this result are novel, and while they donot. appear here asspecific objects of my invention, they re importantand are made the subject matter of the appended claim.

With the foregoing and-other objectsin-view, the invention consists inthe construction, combination and arrangement of parts hereinafterdescribed and illustrated in the drawings, in which:

Fig. 1 is a side elevation of a ball type turret, as usedonaircraft,with parts'broken away to-show my invention as applied to a turretmounted aerial gun.

Fig. 2 is a vertical cross-section looking-from the front of the above'turret, -showing the. drive mechanism'for the sight.

Fig. 3 is a detail cross-sectional view of the turret training gear andmotor, showing also the outline of the fuselage shell.

Fig. 4 is a vertical, longitudinal, sectional view of the front sight.

Fig. 5 is a vertical, cross-sectional view taken on the line 55 of Fig.4.

Fig. 6 is a side elevation of the front sight and shows same applied toa gun with stationary mount, whether upon aircraft, watercraft or landvehicle.

Fig. 7 is a diagrammatic view showing in plan the aiming of a gunequipped with the mechanical front sight, depicting the approach of thetarget 45 off the port bow.

Fig. 8 is a diagrammatic view showing in plan the aim for a target 30off the port stern.

Fig. 9 is a diagrammatic view showing in elevation the approach of atarget at 45 elevation ahead. In each of the diagrammatic views of Figs.7, 8, and 9 the target is assumed to be stationary.

Fig. 10 is a front elevational view of a modification of my invention.

Fig. 11 is a side view of the modification illustrated in Fig. 10, and

Fig. 12 is a plan view of the modification as illustrated in Figs. 10and 11.

Referring now to the drawings, in which Figs. 1, 2 and 3 illustrate myinvention as applied to turret mount machine gun. The turret per se,which forms no part of my invention except as modified to incorporatethe sight adjusting mechanism, is indicated generally at it In Fig. 1part of the turret structure, including the windows H and channel shapedformers or frames l2 are broken away to show the gun mount and sightingmechanism. The fixed machine gun i3 is secured to the turret by means ofthe supporting brackets 2| and 22. The forward bracket 22 is secured tothe channel former or frame 12 and to the forward gun mount adapter 23.The Y bracket 2| is secured to the gun at both the forward and rearadapter 23 and 24 respectively, and to the base of the turret structureat !4.

The turret is supported at the bearing pedestal 25 so as to be rotatableabout the lateral or elevational axis through the trunnion 51. Thereversible variable speed motor 26, with follow-up reduction gearingindicated at 2! is provided for rotating the turret about the lateral orelevational axis to elevate or depress the gun. The base of the bearingpedestals 25 are supported on an inner ring 28. This inner ring 28 isrotatably supported and spaced from an outer ring by means of the upperand lower rollers 29 and 3|. The outer ring 30 is supported by the hullstructure of the aircraft.

A reversible variable speed motor 32 is supported on the base structurel9 formed by the inner ring of the turret and carries a pinion 33 at theouter end of its driveshaft. This pinion is in mesh with a ring gear 34which is secured to the hull supported, outer ring 3!), and pro vides adriving engagement therewith, whereby the turret may be moved about itslongitudinal or azimuthal axis to train the gun. I

The lever 35, Fig. 2, control-s the direction an speed of turretrotation and elevation. Movement of this lever fore and aft results inrotation about the elevational axis, while movement of the leverathwartships results in movement of the turret about the azimuthal axis.The rate -of movement of the lever determines the rate of movement ofthe turret anda diagonal movement of the control lever will result inboth an the drawing.

The forward adjustable bead sight 44 is secured to the recoil guide andslide 36 by means of the bracket 31. For the rear sight I have selectedthe common ring sight 38. This rear ring sight is mounted on the reargun mount adapter 24. I, have previously used the word sight herein asapplying to my device as a whole and also as applying to the specificsighting member such as the bead 40, or the ring sight 38. However,since the sighting members could take some form other than thatdisclosed, I shall hereinafter, for the sake of clarity, refer to thesighting members as the bead and ring sights, although I do not intendto be so limited.

Referring now to Figs. 4 and 5, which show in enlarged views thestructural detail of the bead adjustment. The body 54 of the adjustablebead structure is rotatably supported in a bore 39 of the bracket 31 bymeans of the laterally extending spindle 52, formed integrally with saidbody. The bead 4D is secured to a laterally offset arm 4 I. This arm isrotated about the axis 5-5 of the pivotal stem 45 once for each completerevolution of the turret about its azimuthal axis. The pivotal stem 45is provided with an enlarged collar portion 46 which has an opening 41drilled therein to provide an adjustable support for the arm, so thatthe distance between the center of the bead 40 and the axis of the stem45 may beadjusted for changing air speeds. A set screw 42 is threaded inthe collar 46 so as to engage the arm and hold it in its adjustedposition. As illustrated, the pivotal stem 45 is reduced in crosssectionover .a considerable length at the end opposite the collar. This portionof the shaft is rotatable in the bearing 48 which is held in acylindrical recess formed in the body portion 50 by means of the setscrew 49. The stem 45 is held in the body portion 50 by another setscrew 43 which engages the recessed neck 44 of said stem 45. One end ofthe flexible driveshaft is coupled to the pivotal stem 45, and extendsthrough a flexible housing 56, where its other end is coupled to theworm wheel 52, Fig. 2.

This worm wheel 52 is in mesh with the worm gear 53, which is keyed orotherwise secured to the shaft 54 extending through the hollow trunnionshaft 51. The outer end of this shaft 54 has secured thereto anotherworm gear 6|. This gear is driven by the shaft 63 through the worm wheel62. The shaft 63 is driven by the main take-off gear Ell, shaft 64, andworm 65. The teeth of this main take-off gear mesh with the teeth of thering gear 34 secured to the outer ring 30, so that as the turret istrained about its azimuthal axis the movement of the turret relative tothis outer ring 30 and ring gear 34 is transmitted to the pivotal stem45 and arm 4|.

' The number and size of the gears are selected so that the bead 49 ismovedin a direction opposite to the guns movement and through an equal ag e. 59 that, as the turret is trained to one side .aeeaaca of the;.foreiand aft-axis of the aircraft the: arm 4| which carries the beadtrails behindthe train of the gun and turretby an equal angle andremains parallel to the. line: of 1 flight, irrespective of the angle oftrain.

The; entire body 59. of the adjustable bead structure is. rotatableinthe bore 39 of the bracket 23:7: so that-as the turret :and gunare-movedin elevation about the trunnionshaft 51, the movement istransmitted to the adjustable bead- The spindle 5-2:.carries at itsouter end a beveled ear .66: Thisbeveled gear 66'. is; in mesh with thebeveled-gear 51 which is secured toanend ofrthe stub shaft 68.1This-shaft is rotatable: ina bearing structure similar to thatdescribed: in. conangle. of elevationzbut inazreverse direction, so

thatthe'arrnidlof: the. bead 40 will remain parallel tolthefore and aftaxis of the aircraft, irrespective of the angle of elevation of the gun.

The::two component-.motions above described are imparted .to-the beadindependently: or con- .currentlylwhen the. gun is=moved laterally or:in elevationor insome resultant .of the twodirections of movement; The.distance between the axis 5+5iof the pivotal stem and the plane" of thering sight. asshown in Fig. 1, is proportional to the muzzle velocityofthe bullet, and the distance from theaxis 5-5 to the center of the bead40. is. (with the same function of" velocity) of a length proportionaltothe air speed. The path of the bullet is the resultant of the abovecomponentsof motion and the line of sight should be parallel toorcoincide with the path of the bullet for-stationarytargets at the rangesfor. which these sight .are' efiective.

The important featureof my invention is that the'arm which carries thebead is kept parallel to the: fore and aft-axis of the plane by-keepingthe axis 5- -5= perpendicular to the-roller path ofthe turret, and bytrainingthearm about the axis 5- 5 an amount-equal to the angle of trainof the. turreton itslroller path but inthe opposite direction; Incasethe roller path of the turret is inclined to the fore andaft axis of theplane; it

is only necesary to bend the arm All which carries the bead 40 throughan angle equal to the angle of inclinationof the roller path.

In Figs. 7, .8 and 9, Ihave shown diagrammatically the position of thegun relative to the axis of. the aircraft and the position of the arm 4|for various positions of elevation andtrain of the gun. The rear sightis indicated at 38 and the forward bead sight at 4G. The arrow A ineachfigure shows the direction of flight cfithe "aircraft. In eachfigure the point C' indicates the pnsition of a stationary target, and0C is the line of sight. The lineBD is in the direction of the axis of.thebore of the gun and would be the normal sight line if the bead 45were in the axisb-E of the pivotal stem. This line ED alsorenresentsrthe motion ofthe bullet, due to the explosion of thechargeinzthe chamber of the gun. This wouldbe the true path; of thebulletawere itz not. for I the. motion of the, craft. Therline OCisthecon'ectedsi-ght line as determined by the ring and the bead. Thepath of the bullet is substantially parallel to this line. In each ofthese figures the-line CD represents the component of the velocity ofthe bulletdue to the motion of the aircraft.

It shouldbe noted that in each of the figures the. arm-4i is always.parallel tothe arrow A, indicating thefore and aft axis of the aircraftand the direction of its movement.

Obviously, the sight will function for altitudes higher than illustratedin Fig. 9. In fact, the operator may elevate the turret up to and beyondthe vertical as well as below the horizontal. The obstruction to thebead sight, as viewed from Fig. 2 is not so apparent in Figs. 7, Sand 9,and in actual operation the limited position of elevation and of train,wherein the supporting structure of the movable arm would obstruct thegunners view of the bead, does not affect the usefulness of this sightover the greater part of the hemisphere in which the gun may be pointed.

It is, therefore, apparent that I have devised a useful gun sight for aturret mount which properly and accurately corrects for gunnersdeflection for all angles of elevation and train. My particular gunsight is not, however, limited to use only with a turret mount. In Fig.6 I have illustrated my gun sight asapplied to a standard flexiblymounted machine gun. The gun l3 and the recoil guide and slide member 35are secured to its supporting frame 89 by means of the forward and reargun mount adapters 23 and 24. This assembly, comprising, the gun, recoilguide and slide, mount adapters and supporting frame, is rotatablymounted on the trunnions 8! between thefraine and yoke 82. The yoke $2is mounted for movement about a vertical axis of the pedestal support 83by means of a stem and bearing structure, not shown. The front sightassembly is secured to the recoil guide and slide by means of thebracket 31, while the rear ring sight is mounted directly to the reargun mount adapter 24.

The front sight assembly is identical to that illustrated in Figs. 4 and5, and further description is. unnecessary, except that in the mountinghere illustratedthe flexible driveshaft 55 in the flexible housing 58 iscoupled to the gear 84. This gear is in mesh with the pinion 85, drivenby the larger satellite gear 86 mounted on the opposite end of thepinion shaft. This reduction gearing assembly is shown as journaled inthe supporting frame 8! which is secured to the yoke 82, so as to berotatable therewith about the azimuthal axis of the pedestal mount asthe gun is moved in train. The larger satellite gear 8% ,meshes with andis adapted to roll around the stationary non-rotatable gear 88, which isfastened to the stationary part of the pedestal supporting structure. Asthe gun is swung laterally the yoke 82: turns on its azimuthal axis,carrying with it the gear assembly including the satellite gear 86,which is rotated in its bearing surface driving the pinion and the gear8d. The gear 84 is coupled to an end of the flexible shaft and drivesthe pivotal stem 45 of the adjustable bead til. This causes the arm 41'carrying the bead 49 toswing about the axis 5--5 of the pivotal stem 45.The size ofthe gears are selected so thatthe arm of the head will swingthrough an angle equal to the train of the gun relative tothe fore andaft axis of the craft but .inthe reverse direction.

a .Thegear 8.9 issecured: to.-.the. trunnion. 8l-.by

' gunner.

, of the firing plane.

means of the screws 88 so that its axis is in alignment with the axis ofthe trunnion. The gear 85 is mounted on the frame 86 and as the gun iselevated, the gear Sll'revolves about the stationary gear 39. The gear99 drives the beveled gear 9% which is coupled to the flexibledriveshaft it mounted on the flexible housing H and the beveled gear 61.The beveled gear G meshes with the beveled gear 66 which is secured tothe spindle 52 of the body portion 58 of the bead supporting structure,so that as the gun is elevated or depressed, the arm 45 of the bead atand the body bodying my invention, which I claim to be novel,

are correct for any and all angles of elevation and train.

In Figs. 1G, 11 and 12, I have illustrated a modification of my sightadjusting mechanism. In this embodiment the adjusting mechanism issimilar to that disclosed in Figs. 4 and 5, except that the verticalaxis about which the bead is rotated is laterally offset from thesupporting bracket, so that the supporting bracket will not interferewith the line of sight established by said bead and rear sight.

Fig. 10 illustrates the sight as viewed by the In this figure the arrowindicates the direction of flight of the plane and for the arm H 2 ofthe head E E to take the position illustrated the gun would be trained90 to the right of the 'fore and aft axis of the aircraft, or abreastthe starboard beam. The arm H2 is affixed to and adapted for rotationwith the spindle ifili so that the length of the arm may be adjusted byset screw, for example to correspond to the air speed This spindle issupported in the angular bracket ltll in much the same manner that thepivotal stem =35 is supported in the body 58 as shown in Figs. 4 and 5.The flexible driveshaft 55, enclosed in the flexible housmg 553 iscoupled to this spindle as at E62.

The angular bracket Hit is supported by the horizontal axis E'E. The pinN33 is keyed to the angular bracket iiii at 5%, and this pin isrotatably supported in a bore 896 formed in the main supporting bracket105. The worm gear llli is keyed to this pin so as to be rotated by theworm Ht secured to the end of the spindle Hill. The spindle Hill isrotatable in a bearing formed in the main bracket E35 and held inposition by means of the two collars M39 and Hi]. This spindle fill iscoupled to the flexible shaft l0, as indicated at I 13.

Obviously, the flexible shafts 55 and E6 are each provided with adriving engagement, as illustrated in Figs. 1 to 3, or Fig. 6, so thatas the turret or gun is moved in elevation or train relative to the foreand aft axis of the plane the movement is also transmitted to theangular bracket IM, or the spindle mil, so as to maintain the arm 5'parallel to the fore and aft axis of the aircraft and maintain the axis5'--5' perpensaid roller path,

8 u di'cular to the turret roller path or lateral reference plane.

The circular outline shown in Fig. 11 indicates the path of the centerof the bead H5 as the bracket is rotated about its axis 6'-6', when thebead and arm are in a position from that 11- lustrated in Fig. 10. Thecircular outline shown in Fig. 12 indicates the path of the center ofthe bead as the arm H2 is rotated about the axis 5-5. The particularadvantage of this modification over that disclosed in Figs. 4 and 5 isthus apparent, since as these circular outlines'indicate, the supportingstructure will not interfere with the line of sight at any position ofthe gun relative to the axis of the aircraft.

Other modifications and changes in the number and arrangement of partsmay be made by those skilled in the art without departing from thenature of this invention, within the scope of what is hereinafterclaimed.

The invention described herein may be manufactured and/or used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

I claim:

In combination, a gun turret of the free gun type, a trunnion supporttherefor about which the turret is movable in elevation, a roller pathhaving a stationary portion upon which the turret is movable in train, acompensating gun sight adapted to be mounted to a machine gun mount edin s'aidturret, including a sighting element having a laterally ofiset'arm, a rotatable spindle,

means for securing said arm to said rotatable spindle with said sightingelement laterally offset flexible shaft secured to said spindle andhaving a driven engagement with the stationary portion of whereby themovement of the gun in azimuth about said roller path will betransmitted to the spindle and arm, and means for maintaining the axisof rotation of said spindle perpendicular to the plane of the rollerpath as the turret is elevated about the axis of the trunnions, saidlast namedmeans comprising a rotatable support for the assemblycomprising said spindle, arm, and sighting element, whereby the assemblymay be rotated about an axis normal to the axis of said spindle, andmeans for rotating said support and said assembly about said axiscomprising a flexible shaft having a driving engagement with saidtrunnions whereby the assembly will be rotated as the turret is moved inelevation.

DANIEL V. GALLERY, JR.

REFERENCES orrnl) The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,211,400 Burns Jan. 9, 19171,650,628 Inglis -1 Nov. 29, 1927 2,4411%! Haubroe May 11, 1948 FOREIGNPATENTS Number Country Date 125,146 Great Britain Apr. 17, 1917 215,68?Switzerland July 15, 1941 607,188 Germany Dec. 19, 1934 I 781392 FranceFeb. 25, 1935

